Field of the Invention
The present invention relates to an inerting device, a tank and an aircraft provided with such a device as well as a corresponding method.
The invention relates more specifically to an inerting device for an aircraft fuel tank of the pressurized type, that is to say for a tank provided with a main vessel and with a separate overflow space.
Related Art
An inerting device may be used to protect a fuel tank, in particular of an aircraft such as a fixed-wing airplane or a helicopter, for example.
An inerting device replaces the gaseous headspace of a tank by a gas that is enriched with an inert gas (nitrogen), which can be produced by a generator such as an “OBIGGS”. These tanks are generally connected to the exterior (the atmosphere) by means of an overflow space (sometimes referred to in English as a “venting box”). The overflow space is a space which communicates with the vessel of the tank containing the liquid fuel, although this overflow space does not contain any liquid fuel under normal circumstances.
Document U.S. Pat. No. 8,074,932 relates to a system for the distribution of nitrogen-enriched gas inside an airplane tank that is subjected to ambient pressure. According to this document, during the descent phases of the airplane, nitrogen-enriched gas is injected into a mixing chamber situated between a communicating wing tank and an emergency reserve tank. The wing tank communicates with a central tank, while the emergency reserve tank communicates with the exterior by means of free openings. An oxygen sensor may be provided, as appropriate, within the wing tanks in order to ensure that the distribution system is able to determine whether the concentrations are acceptable.
This device is satisfactory to some extent, although it does not permit the effective use of the nitrogen-enriched air in all circumstances and it requires a mixing box situated between two remote tanks. The detection of the oxygen concentration is difficult, moreover, and does not provide data that are necessary in order to be able to ensure a concentration of oxygen in the entire tank. Finally, this architecture and this function are not well suited to tanks under pressure.